Electrostatic photocopying machine

ABSTRACT

A high voltage means for an electrostatic photocopy machine for charging photosensitive copy paper so that an image of an original document may be superimposed thereon. A wire connected to the high voltage side of a high voltage source is spaced from the sensitive side of the copy paper. A roller positioned in an opposed relationship with the wire moves the copy paper through the high voltage means. The peripheral edge of the roller is electrically conductive and connected to the reference voltage side of the high voltage.

United States Patent Liebens [4 1 June 27, 1972 54] ELECTROSTATIC PHOTOCOPYING 2,965,755 12/1960 West ..250/49.5 zc MACHINE 3,122,634 2/1964 King ..3l7/262 A X [72] Inventor: Raymond B. J. Liebens, Brussels, Belgium prim E i J Miller 73 Assignee: ICP, Inc., Skokie, n1. Bummer-Ham! Mm Attorney-J. Patrick Cagney [22] Filed: March 23, 1970 211 App1.No.: 21,978 [57] ABSTRACT A high voltage means for an electrostatic photocopy machine 521 US. Cl. 317/262 A, 250/49 5 2c chasing that [51] In. CL I D H0 igloo original document may be superimposed thereon. A wire con- [58] dd of snrchmm 5 ZC nected to the high voltage side of a high voltage source is spaced from the sensitive side of the copy paper. A roller posi- 56 um tioned in an opposed relationship with the wire moves the l l R Clad copy paper through the high voltage means. The peripheral fr STATES PATENTS edge of the roller is electrically conductive and connected to the reference voltage side of the high voltage. 2,693,416 11/1954 Butterfield ..317/262 A 3,253,201 5/1966 Slatkin 6 Chins, 1 Drawing Figure PATENTEDJm'! I972 INVENTOR RAYMOND B. J. LIEBENS 2%: wank ATTORNEY BACKGROUND OF THE INVENTION The present invention relates generally to an electrostatic photocopy machine and more particularly relates to the high voltage or corona section of a photocopy machine.

Electrostatic photocopy machines are commonly constructed to pass a specially coated paper such as zinc oxide coated paper into .the machine and electrostatically charging the copy paper prior to transferring the image of an original document through an optical camera system and onto the surface of the charged paper. The exposed or sensitized surface of the copy paperis then generally passed through a liquid toner solution which reacts with the electrostatically charged image borne upon the copy paper surface to develop the image prior to discharge from the machine.

In prior electrostatic photocopying devices the copy paper passing through the high voltage section would charge and cause an adhesion or pulling force between the paper and the charging electrode. Frequently, the adhesion caused considerable movement or fluttering of the copy paper, which often affected the image reproduction. Moreover, the adhesion often was of such sufficient strength to cause creasing and bending of the copy paper which prevented further movement of the copy paper and resulted in a piling up" of the copy paper in and adjacent to the high voltage section. Consequently, it was required to disassemble the copy paper sec tion of the machine to remove the blockage of paper.

SUMMARY'OF INVENTION The subject invention comprises a high voltage electrostatic (corona) section including means for positively guiding the copy paper through the sectionas it is being charged. A wire electrode is connected to one terminal of a high voltage source and a metal roller or an outer metal surface of a roller is connected to the other terminal of the source. The copy paper passes over the roller spaced from the wire.

Accordingly, a primary purpose of the invention is to virtually eliminate a strong adhesive force between the charged copy paper and the charging electrode.

Another object'is to provide positive guide means for the copy paper as it passes through the corona section of the machine.-

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a high voltage section of an electrostatic photocopy machine embodying the principles of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT An electrostatic charging means A electrically charges sensitive copy paper 1-, such as zinc oxide coated paper, so that it is suitable to receive the image of an original document transferred through a camera means (not shown) of an electrostatic photocopy machine.

The sensitive paper is guided through the electrostatic means A by two flat pieces 2 and 3 and an electrically conductive roller 4 interposed therebetween. Roller 4 is placed substantially tangent to the plane determined by the flat pieces 2 and 3, so that the copy paper sheet 1 contacts the roller. The roller may be formed, for example, from a silvered plastic material; it may be constructed entirely of metal or just the outer peripheral surface thereof.

A high voltage wire electrode 5 extends between an insulating piece 6 on one side and an identical piece on the opposite side (not shown). Wire 5 is connected to terminal 7b of the high voltage source 7. The other temiinal 7b of the high voltage source 7 is connected electrically to the roller 4. The high voltage electrode 5 may be positive or negative with respect to a reference or ground. The high voltage may include a high fre uenc (HF) corn nent.

2 brush comprising a multitude of metal or metalized hairs 8 is mounted in a casing 9. The outer tips of the hairs 8 contact roller 4 for the purpose primarily to conduct to ground the HF currents which circulate over the surface of roller 4 due to the skin efiect phenomenon, and thereby assuring a more positive electrical contact between the source 7 and the roller 4.

Roller 4 is rotatably mountedin casing 9. A chain wheel 10 rotated by an endless revolving chain (not shown) may be used to drive the roller 4.

The roller 4 rotates with a peripheral speed at least equal to the velocity of the copy paper sheet 1 and preferably faster, for the purpose of continuously releasing the copy paper 1 and to prevent clinging and adhesion between the roller and copy paper due tothe charging of the sensitive side of the paper by the highvoltage between wire electrode 5 and roller 4.

The description of the preferred embodiment of this invention is intended merely as illustrative of this invention, the scope and limits of which are set forth in the following claims.

I claim:

1. In an electrostatic photocopying machine of the type wherein photosensitive copy paper is electrostatically charged before photocopying an image of an original document onto said charged copy paper, electrostatic means for charging said copy paper comprising:

a high voltage source having a first terminal and a second terminal;

a wire electrode connected to one of said terminals;

a roller having an electrical conducting surface, said surface being connected to the other said terminal, said wire electrode and said roller being spaced apart in substantially parallel relationship to provide therebetween a charging zone through which copy paper may be passed to acquire an electrostatic charge; and

a brush comprising a plurality of electrically conductive hairs disposed adjacent said roller but remote from said wire electrode, the outer tips of said hairs contacting the surface of said roller.

2. The photocopying machine of claim 1 wherein an elongated infeed guide plate is provided adjacent said roller in substantially tangential relation with the portion of said roller nearest said wire electrode so that copy paper fed across said guide plate to said roller is in engagement therewith as it passes through said charging zone.

3. The photocopying machine of claim 2 wherein a roller drive means is provided for rotating the roller at a peripheral rate of rotational movement of at least substantially the rate of movement of the copy paper through the photocopy machine.

4. The photocopying machine of claim 2 wherein said first terminal of said high voltage source is at a high voltage, said second terminal is at a reference voltage and said wire electrode is connected to said first terminal.

5. The photocopying machine of claim 1 wherein said brush provides a substantially low resistance path from said roller to said reference voltage.

6. The photocopying machine of claim 5 wherein said reference voltage is at the ground potential of the machine. 

1. In an electrostatic photocopying machine of the type wherein photosensitive copy paper is electrostatically charged before photocopying an image of an original document onto said charged copy paper, electrostatic means for charging said copy paper comprising: a high voltage source having a first terminal and a second terminal; a wire electrode connected to one of said terminals; a roller having an electrical conducting surface, said surface being connected to the other said terminal, said wire electrode and said roller being spaced apart in substantially parallel relationship to provide therebetween a charging zone through which copy paper may be passed to acquire an electrostatic charge; and a brush comprising a plurality of electrically conductive hairs disposed adjacent said roller but remote from said wire electrode, the outer tips of said hairs contacting the surface of said roller.
 2. The photocopying machine of claim 1 wherein an elongated infeed guide plate is provided adjacent said roller in substantially tangential relation with the portion of said roller nearest said wire electrode so that copy paper fed across said guide plate to said roller is in engagement therewith as it passes through said charging zone.
 3. The photocopying machine of claim 2 wherein a roller drive means is provided for rotating the roller at a peripheral rate of rotational movement of at least substantially the rate of movement of the copy paper through the photocopy machine.
 4. The photocopying machine of claim 2 wherein said first terminal of said high voltage source is at a high voltage, said second terminal is at a reference voltage and said wire electrode is connected to said first terminal.
 5. The photocopying machine of claim 1 wherein said brush provides a substantially low resistance path from said roller to said reference voltage.
 6. The photocopying machine of claim 5 wherein said reference voltage is at the ground potential of the machine. 